Exposure categories

The NCRP has long recognized the need for a clear assessment of
the magnitude of doses from various sources of radiation to which
the population of the U.S. is exposed. In anticipation of the need to
gather data for input into this process, five assessment committees,
each addressing a different source category, were established. NCRP
reports assessing exposures from natural background, consumer
products, nuclear power generation, and diagnostic medical radiation
have been published (NCRP, 1987a,b,c,d, NCRP, 1989)....

The NCRP has long mcog&ed the need for a clear assessment of the
magnitude of doses from various souroes of radiation to which the
population of the U.S. is ocpo9ed. In anticipation of the need to gather
data for input into this process five as&sament committees, each
adhing a different source category, wem established, first in 1971
and then reestablished in 1986. NCRP reports assessing exposum
from natural background, consumer products, and nuclear power gene
ation have recently been published (NCRP, 1987% 1987b. 1987~)...

The French work was based on the available Black Smoke (BS) data. A correlation analysis between
BS and PM10 (TEOM method7
) was first carried out. It was found that at urban background sites, BS
and PM10 (TEOM) are about equal. Following this, linear relationships were sought between the BS
data and land use categories in the areas surrounding the measurement sites. Multiple regression
analysis was performed for three categories of sites: urban, suburban and rural. Based on these
regressions and using the land use data set, a PM10 map was established.

Furthermore, the particular bus in which the commuter
travelled during this week was not air conditioned so
ventilation was provided by open windows, allowing air to
flow freely in and out of the bus. This is an interesting result
as it demonstrates that due to the high temporal and spatial
variability in CO concentrations, other variables (such as
ventilation rate and proximity to emissions) may be more
important in determining exposure than choice of transport
mode.

The biologic phenotype underlying chronic periodontitis, including the biofilm and the host
response, tend to vary among individuals despite a similar clinical diagnostic category
(Offenbacher et al. 2007). Consequently, disease screening should ideally be based on
clinical determinations and the biologic phenotype (Page and Kornman 1997). Other
associated factors include environmental exposures, as well as differences in genetic and
possibly epigenetic composition (Page and Kornman 1997).

Natural photoprotection is provided by structural proteins in the epidermis, particularly keratins and melanin. The amount of melanin and its distribution in cells is genetically regulated, and individuals of darker complexion (skin types IV–VI) are at decreased risk for the development of acute sunburn and cutaneous malignancy.
Other forms of photoprotection include clothing and sunscreens. Clothing constructed of tightly woven sun-protective fabrics, irrespective of color, affords substantial protection. Wide-brimmed hats, long sleeves, and trousers all reduce direct exposure.